CN116293787B - A combustion device combining plasma and blunt body stable flame - Google Patents

Abstract

The invention relates to a combustion device combining plasma and a blunt body to stabilize flame, which comprises an upstream flame stabilizing structure and a downstream pipeline structure, wherein the upstream flame stabilizing structure comprises an outer shell, an igniter assembly and a blunt body assembly, the blunt body assembly comprises a blunt body bracket, a first blunt body, a second blunt body and a fixed baffle, and the first blunt body and the second blunt body are both electrically connected with a high-voltage plasma power supply; a blunt body gap is reserved between the first blunt body and the second blunt body, a fixed baffle is positioned on one side of the first blunt body and the second blunt body, which faces to the downstream pipeline structure, a horizontal gap is reserved between the fixed baffle and the first blunt body and the second blunt body, the fixed baffle comprises two fixed sub-plates, a vertical gap matched with the blunt body gap is reserved between the two fixed sub-plates, one end of each fixed sub-plate is connected with a movable baffle, and the movable baffle is used for switching and sealing the horizontal gap and the vertical gap. Compared with the prior art, the invention has the advantages of improving the combustion efficiency, widening the stable combustion boundary and the like.

Description

A combustion device combining plasma and blunt body stable flame

Technical Field

The invention relates to the field of combustion devices, in particular to a combustion device combining plasma and blunt body stable flame.

Background technique

When the gas flows through the bluff body, a recirculation zone is formed behind the bluff body. This characteristic is often used to stabilize the flame in the case of high-speed incoming flow, which is of great significance in engineering practice. Therefore, bluff body stabilizers are widely used in the afterburner of military engines and the micro-scale combustion chamber of drones. The combustion stability of the afterburner is of great military significance due to the harsh combustion environment and extreme operating conditions. Micro-scale burners are small in size, resulting in severe heat dissipation, short gas residence time, insufficient chemical reaction, difficulty in ignition, and low combustion efficiency. They also require stabilization measures such as bluff bodies. How to expand the range of stable combustion conditions, ensure the stable combustion of the bluff body flame, and further improve the combustion rate and efficiency has become a current research hotspot.

As an advanced technology that can improve combustion performance, plasma combustion-supporting technology has shown broad application prospects in improving the uniformity of the temperature field at the outlet of the combustion chamber, widening the stable combustion range, and improving the combustion efficiency, and has received widespread attention from the industry. Since the 1970s, many studies have been carried out at home and abroad on the development of plasma combustion-supporting exciters, mainly using dielectric barrier discharge to generate plasma. In recent years, sliding arc discharge has also received widespread attention. The electron temperature of sliding arc discharge plasma is low, but the electron number density is high, which has typical low-temperature plasma characteristics. Compared with other discharge methods such as dielectric barrier discharge to generate plasma, sliding arc discharge has the advantages of simple electrode structure, continuous discharge without electrode ablation, and no need for water cooling. In addition, the high-energy electrons and active groups generated during the sliding arc discharge process are highly chemically active. These active particles can increase the chemical reaction rate and accelerate the chemical reaction process. Therefore, sliding arc discharge plasma has broad application prospects in fuel reforming, pollutant degradation, sewage treatment, plasma ignition and combustion-supporting.

Summary of the invention

The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a combustion device combining plasma and blunt body stable flame. The different combustion states of the two-dimensional blunt body flame are monitored in real time, and the spatial position of the plasma combustion-aiding device is optimized and adjusted on this basis, so as to achieve the purpose of improving combustion efficiency and broadening the stable combustion boundary.

The purpose of the present invention can be achieved by the following technical solutions:

A combustion device combining plasma and bluff body flame stabilization, comprising an upstream flame stabilization structure and a downstream pipeline structure, wherein the upstream flame stabilization structure comprises an outer shell, an igniter assembly and a bluff body assembly installed in the outer shell, wherein the bluff body assembly comprises a bluff body bracket, and a first bluff body, a second bluff body and a fixed baffle supported by the bluff body bracket, wherein the first bluff body and the second bluff body are both electrically connected to a high-voltage plasma power supply;

A bluff body gap is left between the first bluff body and the second bluff body, the fixed baffle is located on the side of the first bluff body and the second bluff body facing the downstream pipeline structure, and a horizontal gap is left between the first bluff body and the second bluff body, the fixed baffle includes two fixed sub-plates, a vertical gap matching the bluff body gap is left between the two fixed sub-plates, one end of each of the fixed sub-plates is connected to a movable baffle, and the movable baffle is used to switch and close the horizontal gap and the vertical gap.

Furthermore, the movable baffle can be rotatably connected to the bluff support and switch between a first state and a second state. When the movable baffle is in the first state, the ends of the movable baffles on the two fixed sub-plates are connected to close the vertical gap.

When the movable baffles are in the second state, each of the movable baffles respectively closes the horizontal gap on one side of the corresponding fixed sub-plate.

Further, when the movable baffle is in the first state, the active particles generated by the first bluff body and the second bluff body and the incoming flow through the igniter assembly sequentially pass through the bluff body gap and the horizontal gap, and enter the downstream pipe structure from both sides of the upstream flame stabilization structure;

When the movable baffle is in the second state, the active particles generated by the first and second bluff bodies and the incoming flow through the igniter assembly pass through the bluff body gaps and the vertical gaps in sequence and enter the downstream pipe structure from the middle of the upstream flame stabilization structure.

Furthermore, the movable baffle is also connected to a rotation drive structure, which includes a motor, a reduction mechanism and a transmission shaft connected in sequence, the motor and the reduction mechanism are both installed on the blunt body bracket, and the transmission shaft is connected to the movable baffle.

Furthermore, the bluff support is also provided with an air extraction hole, which is located on the side of the fixed baffle plate facing the downstream pipeline structure, and the combustion device also includes an unburned material concentration detection structure and a controller, the detection end of the unburned material concentration detection structure is connected to the air extraction hole, and the controller is respectively connected to the unburned material concentration detection structure and the motor;

The control process of the controller includes:

When the flame is judged to be stably burning according to the output result of the unburned matter concentration detection structure, the control motor drives the movable baffle to be in the first state, so that the gas passing through the slit of the bluff body enters the two sides of the bluff body through the horizontal slit;

When the flame is judged to be unstable combustion according to the output result of the unburned material concentration detection structure, the control motor drives the movable baffle to be in the second state, so that the gas passing through the bluff body gap enters the downstream of the bluff body through the vertical gap, further enhancing the combustion at the spatial position of the exhaust hole.

Furthermore, the rotary drive structure also includes a motor sealing cover, the motor and the reduction mechanism are both located inside the motor sealing cover, the motor sealing cover is fixed to the blunt body bracket through bolts and a sealing ring, and the electric wires of the motor are led out through an aviation connector to connect to the controller.

Furthermore, the first bluff body and the second bluff body are provided with mutually parallel blocking media on both sides of the bluff body gap.

Furthermore, the size of the bluff body gap gradually increases from an end facing the upstream flame stabilization structure to an end facing the downstream pipeline structure.

Furthermore, the first bluff body and the second bluff body are both made of metal materials, and the fixed baffle and the movable baffle are both made of high temperature resistant ceramic materials.

Further, the outer shell includes an upstream square tube and an upstream flange fixed to the end of the upstream square tube, the downstream pipeline structure includes a downstream square tube and a downstream flange fixed to the end of the downstream square tube, and the upstream flange is connected to the downstream flange;

The igniter assembly comprises an igniter fixing part and an igniter. The igniter fixing part is fixed on the inner wall of the upstream square tube, and the igniter is installed on the igniter fixing part.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention combines plasma combustion assistance with a blunt body flame stabilization structure. By changing the flow field structure of the blunt body flame stabilization, part of the gas can enter the recirculation zone through the plasma discharge area located in the gap of the blunt body structure, thereby enhancing the combustion of the flame inside the recirculation zone, thereby improving the flame combustion efficiency, enhancing the flame combustion stability, and widening the flameout limit.

(2) The present invention combines the plasma discharge state with the combustion state, and realizes the stability of plasma at different positions of the flame under the premise of sealing and insulation, and has good adaptability to working conditions.

(3) The present invention can change the specific position of plasma combustion-assisted combustion based on the flame state and optimize the combustion organization mode of flame stabilization.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the overall structure of a combustion device combining plasma and blunt body stabilized flame provided in an embodiment of the present invention;

2 is a schematic cross-sectional view of a flame stabilization portion of a combustion device combining plasma and blunt body flame stabilization provided in an embodiment of the present invention;

FIG3 is a partial structural schematic diagram of an igniter (22) of a combustion device combining plasma and blunt body stable flame provided in an embodiment of the present invention;

FIG4( a ) is a schematic diagram of a bluff body portion provided in an embodiment of the present invention;

FIG4( b ) is a schematic diagram of the spatial position of a movable baffle ( 35 ) of a bluff body portion during stable combustion in the exhaust hole region provided in an embodiment of the present invention;

FIG4( c ) is a schematic diagram of the spatial position of a movable baffle of a bluff body portion when unstable combustion occurs in the exhaust hole region, provided in an embodiment of the present invention;

FIG5 is a schematic diagram of a blunt body portion in a gliding arc plasma discharge mode provided in an embodiment of the present invention;

FIG6( a ) is an overall schematic diagram of a connection portion between a motor and a movable baffle provided in an embodiment of the present invention;

FIG6( b ) is a partial schematic diagram of the connection between a motor and a movable baffle provided in an embodiment of the present invention;

FIG7 is a plasma combustion-supporting position control logic diagram provided in an embodiment of the present invention;

In the figure, 1. outer shell, 11. upstream square tube, 12. upstream flange, 2. igniter assembly, 21. igniter fixing part, 22. igniter, 23. discharge electrode, 3. blunt body assembly, 31. blunt body bracket, 311. exhaust hole, 312. motor shaft hole, 32. first blunt body, 33. second blunt body, 34. fixed baffle, 35. movable baffle, 36. blunt body gap, 37. horizontal gap, 38. vertical gap, 39. blocking medium, 4. rotary drive structure, 41. motor, 42. reduction mechanism, 43. transmission shaft, 44. motor sealing cover, 5. downstream pipeline structure, 51. downstream square tube, 52. downstream flange, 6. bolts, 7. nuts, 8. gaskets, 9. high-voltage wires, 10. ceramic tube.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition and explanation in the subsequent drawings.

In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

Example 1

As shown in FIG. 1-4( a ), the present embodiment provides a combustion device combining plasma and a bluff body stabilizing flame, comprising an upstream flame stabilizing structure and a downstream pipeline structure 5, wherein the upstream flame stabilizing structure comprises an outer shell 1 and an igniter assembly 2 and a bluff body assembly 3 installed in the outer shell 1, wherein the bluff body assembly 3 comprises a bluff body bracket 31 and a first bluff body 32, a second bluff body 33 and a fixed baffle 34 supported by the bluff body bracket 31, wherein the first bluff body 32 and the second bluff body 33 are both electrically connected to a high-voltage plasma power supply;

A bluff body gap 36 is left between the first bluff body 32 and the second bluff body 33. The fixed baffle 34 is located on one side of the first bluff body 32 and the second bluff body 33 facing the downstream pipeline structure 5, and a horizontal gap 37 is left between the first bluff body 32 and the second bluff body 33. The fixed baffle 34 includes two fixed sub-plates, and a vertical gap 38 matching the bluff body gap 36 is left between the two fixed sub-plates. One end of each fixed sub-plate is connected to a movable baffle 35, and the movable baffle 35 is used to switch and close the horizontal gap 37 and the vertical gap 38.

The discharge mode of the first bluff body 32 and the second bluff body 33 can be DBD dielectric barrier discharge or sliding arc plasma discharge;

During DBD dielectric barrier discharge, the first bluff body 32 and the second bluff body 33 are provided with mutually parallel barrier dielectrics 39 on both sides of the bluff body gap 36. At this time, the bluff body gap 36 is a plasma discharge area.

During the sliding arc plasma discharge, as shown in FIG5 , the blunt body gap 36 gradually increases in size from one end facing the upstream flame stabilization structure to the end facing the downstream pipe structure 5. At this time, the blunt body gap 36 is a sliding arc discharge area. Under the action of the airflow, the discharge arc gradually moves downstream and continues to lengthen until it breaks, and then discharges again at the shortest position of the two blunt bodies, and the cycle is repeated to achieve a better plasma combustion-supporting effect.

In this solution, the active particles stimulated by the first bluff body 32 and the second bluff body 33 have the effect of stabilizing the flame, and a fixed baffle 34 and a rotatable movable baffle 35 are provided to enhance the flame at different positions according to the flame combustion conditions in the internal area, thereby improving the overall combustion efficiency and widening the stable combustion boundary.

The igniter assembly 2 and the downstream pipeline structure 5 respectively realize the installation of the igniter 22 and provide the function of the downstream pipeline, which can be achieved through similar solutions in the prior art and are not limited to the only solution.

Specifically, for the structure in the bluff assembly, the movable baffle 35 can be rotatably connected to the bluff support 31 and switch between the first state and the second state. As shown in FIG. 4( b ), when the movable baffle 35 is in the first state, the ends of the movable baffles 35 on the two fixed sub-plates are connected to close the vertical gap 38;

As shown in FIG. 4( c ), when the movable baffles 35 are in the second state, each movable baffle 35 closes the horizontal gap 37 on one side of the corresponding fixed sub-plate.

When the movable baffle 35 is in the first state, the active particles generated by the first bluff body 32 and the second bluff body 33 and the incoming flow through the igniter assembly 2 sequentially pass through the bluff body gap 36 and the horizontal gap 37, and enter the downstream pipe structure 5 from both sides of the upstream flame stabilization structure;

When the movable baffle 35 is in the second state, the active particles generated by the first bluff body 32 and the second bluff body 33 and the incoming flow through the igniter assembly 2 sequentially pass through the bluff body gap 36 and the vertical gap 38 and enter the downstream pipe structure 5 from the middle of the upstream flame stabilization structure.

As a preferred embodiment, in order to realize automatic control of the above-mentioned combustion device, as shown in Figures 6(a) and 6(b), the movable baffle 35 is also connected to a rotation drive structure 4, which includes a motor 41, a reduction mechanism 42 and a transmission shaft 43 connected in sequence, and the motor 41 and the reduction mechanism 42 are both installed on the blunt body bracket 31, and the transmission shaft 43 is connected to the movable baffle 35.

The bluff support 31 is also provided with an air extraction hole 311, which is located on the side of the fixed baffle 34 facing the downstream pipeline structure 5. The combustion device also includes an unburned material concentration detection structure and a controller. The detection end of the unburned material concentration detection structure is connected to the air extraction hole 311, and the controller is respectively connected to the unburned material concentration detection structure and the motor 41;

The control process of the controller includes:

When the flame is determined to be stably burning according to the output result of the unburned matter concentration detection structure, the control motor 41 drives the movable baffle 35 to be in the first state, so that the gas passing through the slit 36 of the bluff body enters the two sides of the bluff body through the horizontal slit 37;

When the flame is judged to be unstable combustion according to the output result of the unburned material concentration detection structure, the control motor 41 drives the movable baffle 35 to be in the second state, so that the gas passing through the blunt body gap 36 enters the downstream of the blunt body through the vertical gap 38, further enhancing the combustion at the spatial position of the exhaust hole 311.

Thus, when it is detected that the area where the gas extraction hole 311 is located is in stable combustion, the plasma-rich gas in the flow channel between the two bluff bodies will enter the two sides of the bluff bodies through the horizontal flow channel and be directly injected into the shear layer area, further stabilizing the flame;

When the area where the gas extraction hole 311 is located is detected to be in unstable combustion, the plasma-rich gas in the flow channel between the two bluff bodies will enter the downstream of the bluff body through the vertical flow channel, further enhancing the combustion at the spatial position of the gas extraction hole 311;

Therefore, the specific location of plasma combustion can be changed based on the flame state, and the combustion organization mode of flame stabilization can be optimized.

Since there is a gap between the transmission shaft 43 and the side wall, the motor 41 needs to be sealed. Preferably, the rotary drive structure 4 also includes a motor sealing cover 44. The motor 41 and the reduction mechanism 42 are both located on the inner side of the motor sealing cover 44. The motor sealing cover 44 is fixed to the blunt body bracket 31 by bolts and sealing rings. The wires of the motor 41 are connected to the controller through an aviation connector.

Based on the configuration of the motor sealing cover 44 , the motor 41 and the speed reduction mechanism 42 can be installed on the side wall of the bluff body bracket 31 or on the motor sealing cover 44 .

Preferably, the first bluff body 32 and the second bluff body 33 are both made of metal materials, and the fixed baffle 34 and the movable baffle 35 are both made of high temperature resistant ceramic materials.

Preferably, the outer shell 1 includes an upstream square tube 11 and an upstream flange 12 fixed to the end of the upstream square tube 11, the downstream pipeline structure 5 includes a downstream square tube 51 and a downstream flange 52 fixed to the end of the downstream square tube 51, and the upstream flange 12 is connected to the downstream flange 52;

A gasket 8 is provided between the upstream flange 12 and the downstream flange 52 , and the upstream flange 12 and the downstream flange 52 are fixedly connected by bolts 6 and nuts 7 .

The igniter assembly 2 includes an igniter fixing part 21 and an igniter 22. The igniter fixing part 21 is fixed to the inner wall of the upstream square tube 11 by bolts 6. The igniter 22 is installed on the igniter fixing part 21. The end of the igniter 22 leads to a discharge electrode 23 for ignition.

A more optimal implementation can be obtained by combining the above preferred implementation modes in any way. The following specifically describes an optimal implementation mode obtained by combining all the implementation modes.

The overall device provided in this embodiment is divided into two parts: a downstream pipeline part and an upstream flame stabilization part, the two parts are connected by a flange, and a graphite gasket is placed at the connection to achieve sealing. In actual operation, the premixed gas of fuel and air enters through the upstream pipeline inlet, and flows through the upstream pipeline, the igniter 22, the bluff body and the downstream pipeline in sequence.

The downstream pipeline part is mainly connected by square pipes and flanges through welding, and the material is heat-resistant metal.

The overall structure of the flame stabilization part of the upstream pipeline is shown in Figure 2. The exterior is welded by a square tube and a flange, and the internal igniter 22 part is shown in Figure 3. The discharge electrode material of the igniter 22 extending into the cavity is metal, and the main body of the igniter 22 is ceramic. When the igniter 22 is ignited, an electric spark discharge occurs between the positive and negative electrodes, and a fire core is generated in the unburned gas. The fire core moves downstream under the impetus of the incoming flow, and finally stabilizes the flame downstream of the blunt body. The main body of the igniter 22 and the side wall are fixedly connected by the igniter fixing part 21 and the bolts, and the main body of the igniter 22 and the igniter fixing part 21 are sealed by high-temperature glue.

The bluff body is shown in FIG4 . The brackets at both ends of the bluff body are made of high temperature resistant insulating ceramics. The triangular bluff bodies on both sides are made of metal materials and are connected to the high voltage plasma power supply by wires passing through the side walls. The wires and the side walls are insulated by ceramic tubes (as shown in FIG2 ). A gap is left in the middle of the triangular bluff bodies on both sides. The two sides of the gap are parallel blocking media 39. The middle gap is the plasma discharge area. The triangular bluff body, the fixed baffle 34 and the movable baffle 35 are fixed to the insulating ceramic brackets on both sides by grooves. In actual applications, unburned gas will flow through the discharge area, and the heat generated in the discharge area and the active particles excited by the plasma will enter the downstream of the bluff body to further stabilize the flame.

In addition, the device can further change the DBD dielectric barrier discharge into a sliding arc plasma discharge. By changing the shape of the blunt body, the distance between the two blunt bodies is gradually changed. As shown in FIG5 , under the action of the airflow, the discharge arc gradually moves downstream and continues to lengthen until it is broken, and then discharges again at the shortest position of the two blunt bodies, and the cycle is repeated to achieve a better plasma combustion-supporting effect.

This device is based on a mechanical structure to achieve the adjustment of the plasma combustion-supporting position. The mechanical structure is composed of a motor 41 and a movable baffle 35, and the connection between the two is shown in Figure 6. The motor 41 and the reduction mechanism 42 are connected to the movable baffle 35 through a transmission shaft 43. For the convenience of installation, this part is connected using a mortise and tenon structure. Since there is a gap between the transmission shaft 43 and the side wall, it is necessary to seal the motor 41 part. The specific sealing method is shown in Figure 6 (a). The motor sealing cover 44 is fixed to the side wall by bolts and a sealing ring, and the wires of the motor 41 are connected to the controller through a dedicated aviation connector.

The logic diagram of the plasma combustion-supporting position control is shown in FIG7 . First, part of the gas is extracted through the exhaust hole 311 downstream of the bluff body. According to the concentration of unburned substances (hydrocarbon mixture, carbon monoxide, etc.) in the gas and the real-time flame state of the area, the flame in the area is judged, and the baffle state is further determined. When the gas sample detection result is determined to be stable combustion, the spatial position of the movable baffle 35 is as shown in FIG4(b). At this time, the plasma-rich gas in the flow channel between the two bluff bodies will enter the two sides of the bluff body through the horizontal flow channel and directly inject into the shear layer area to further stabilize the flame. When the gas sample detection result is determined to be unstable combustion, the spatial position of the movable baffle 35 is as shown in FIG4(c). At this time, the plasma-rich gas in the flow channel between the two bluff bodies will enter the downstream of the bluff body through the vertical flow channel, further enhancing the combustion at the spatial position of the exhaust hole 311. When the flame at this position is stable (less unburned substances in the gas sample), the spatial position of the movable baffle 35 is changed to FIG4(b). Because the movable baffle 35 and the fixed baffle 34 inside the flow channel are in the high temperature area, the baffle should be made of high temperature resistant ceramic material.

The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims (10)

1. A combustion device combining plasma and blunt body flame stabilization, comprising an upstream flame stabilization structure and a downstream pipeline structure (5), characterized in that the upstream flame stabilization structure comprises an outer shell (1) and an igniter assembly (2) and a blunt body assembly (3) installed in the outer shell (1), the blunt body assembly (3) comprises a blunt body bracket (31) and a first blunt body (32), a second blunt body (33) and a fixed baffle (34) supported by the blunt body bracket (31), the first blunt body (32) and the second blunt body (33) are both electrically connected to a high-voltage plasma power supply; A bluff body gap (36) is left between the first bluff body (32) and the second bluff body (33); the fixed baffle (34) is located on one side of the first bluff body (32) and the second bluff body (33) facing the downstream pipeline structure (5), and a horizontal gap (37) is left between the first bluff body (32) and the second bluff body (33); the fixed baffle (34) includes two fixed sub-plates, a vertical gap (38) matching the bluff body gap (36) is left between the two fixed sub-plates, and one end of each of the fixed sub-plates is connected to a movable baffle (35), and the movable baffle (35) is used to switch and close the horizontal gap (37) and the vertical gap (38). 2. A combustion device combining plasma and blunt body flame stabilization according to claim 1, characterized in that the movable baffle (35) is rotatably connected to the blunt body bracket (31) and is switchable between a first state and a second state, and when the movable baffle (35) is in the first state, the ends of the movable baffles (35) on the two fixed sub-plates are connected to close the vertical gap (38); When the movable baffles (35) are in the second state, each of the movable baffles (35) respectively closes the horizontal gap (37) on one side of the corresponding fixed sub-plate. 3. A combustion device combining plasma and blunt body flame stabilization according to claim 2, characterized in that when the movable baffle (35) is in the first state, the active particles generated by the first blunt body (32) and the second blunt body (33) and the incoming flow passing through the igniter assembly (2) pass through the blunt body gap (36) and the horizontal gap (37) in sequence, and enter the downstream pipeline structure (5) from both sides of the upstream flame stabilization structure; When the movable baffle (35) is in the second state, the active particles generated by the first bluff body (32) and the second bluff body (33) and the incoming flow passing through the igniter assembly (2) pass through the bluff body gap (36) and the vertical gap (38) in sequence and enter the downstream pipe structure (5) from the middle of the upstream flame stabilization structure. 4. A combustion device combining plasma and blunt body stable flame according to claim 2, characterized in that the movable baffle (35) is also connected to a rotary drive structure (4), the rotary drive structure (4) comprises a motor (41), a reduction mechanism (42) and a transmission shaft (43) connected in sequence, the motor (41) and the reduction mechanism (42) are both supported by a blunt body bracket (31), and the transmission shaft (43) is connected to the movable baffle (35). 5. A combustion device combining plasma and blunt body stable flame according to claim 4, characterized in that an air extraction hole (311) is also provided on the blunt body bracket (31), and the air extraction hole (311) is located on the side of the fixed baffle (34) facing the downstream pipeline structure (5), and the combustion device also includes an unburned material concentration detection structure and a controller, the detection end of the unburned material concentration detection structure is connected to the air extraction hole (311), and the controller is respectively connected to the unburned material concentration detection structure and the motor (41); The control process of the controller includes: When the flame is judged to be stably burning according to the output result of the unburned matter concentration detection structure, the control motor (41) drives the movable baffle (35) to be in the first state, so that the gas passing through the slit (36) of the bluff body enters the two sides of the bluff body through the horizontal slit (37); When the flame is judged to be unstable combustion according to the output result of the unburned material concentration detection structure, the control motor (41) drives the movable baffle (35) to be in the second state, so that the gas passing through the bluff body gap (36) enters the downstream of the bluff body through the vertical gap (38), further enhancing the combustion at the spatial position of the exhaust hole (311). 6. A combustion device combining plasma and blunt body stable flame according to claim 5, characterized in that the rotary drive structure (4) also includes a motor sealing cover (44), the motor (41) and the reduction mechanism (42) are both located on the inner side of the motor sealing cover (44), the motor sealing cover (44) is fixed to the blunt body bracket (31) by bolts and a sealing ring, and the wires of the motor (41) are led out through an aviation connector to connect to the controller. 7. A combustion device combining plasma and blunt body flame stabilization according to claim 1, characterized in that the first blunt body (32) and the second blunt body (33) are provided with mutually parallel blocking media (39) on both sides of the blunt body gap (36). 8. A combustion device combining plasma and blunt body flame stabilization according to claim 1, characterized in that the blunt body gap (36) gradually increases in size from one end facing the upstream flame stabilization structure to one end facing the downstream pipeline structure (5). 9. A combustion device combining plasma and blunt body stable flame according to claim 1, characterized in that the first blunt body (32) and the second blunt body (33) are both made of metal materials, and the fixed baffle (34) and the movable baffle (35) are both made of high temperature resistant ceramic materials. 10. A combustion device combining plasma and blunt body flame stabilization according to claim 1, characterized in that the outer shell (1) comprises an upstream square tube (11) and an upstream flange (12) fixed to the end of the upstream square tube (11), the downstream pipeline structure (5) comprises a downstream square tube (51) and a downstream flange (52) fixed to the end of the downstream square tube (51), and the upstream flange (12) is connected to the downstream flange (52) by bolts (6); The igniter assembly (2) comprises an igniter fixing member (21) and an igniter (22); the igniter fixing member (21) is fixed on the inner wall of the upstream square tube (11); and the igniter (22) is mounted on the igniter fixing member (21).